On Thu, Jun 01, 2023 at 05:18:11PM +0200, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@xxxxxxxx> > > Combining UBSAN and GCOV in randconfig builds results in a number of > stack frame size warnings, such as: > > crypto/twofish_common.c:683:1: error: the frame size of 2040 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] > drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_req_lat_if.c:1589:1: error: the frame size of 1696 bytes is larger than 1400 bytes [-Werror=frame-larger-than=] > drivers/media/platform/verisilicon/hantro_g2_vp9_dec.c:754:1: error: the frame size of 1260 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] > drivers/staging/media/ipu3/ipu3-css-params.c:1206:1: error: the frame size of 1080 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] > drivers/staging/media/rkvdec/rkvdec-vp9.c:1042:1: error: the frame size of 2176 bytes is larger than 2048 bytes [-Werror=frame-larger-than=] > drivers/staging/media/rkvdec/rkvdec-vp9.c:995:1: error: the frame size of 1656 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] > > I managed to track this down to the -fsanitize=bounds option clashing > with the -fprofile-arcs option, which leads a lot of spilled temporary > variables in generated instrumentation code. > > Hopefully this can be addressed in future gcc releases the same way > that clang handles the combination, but for existing compiler releases, > it seems best to disable one of the two flags. This can be done either > globally by just not passing both at the same time, or locally using > the no_sanitize or no_instrument_function attributes in the affected > functions. > > Try the simplest approach here, and turn off -fsanitize=bounds on > gcc when GCOV is enabled, leaving the rest of UBSAN working. Doing > this globally also helps avoid inefficient code from the same > problem that did not push the build over the warning limit. > > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> > Link: https://lore.kernel.org/stable/6b1a0ee6-c78b-4873-bfd5-89798fce9899@kili.mountain/ > Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110074 > Link: https://godbolt.org/z/zvf7YqK5K > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> I think more production systems will have CONFIG_UBSAN_BOUNDS enabled (e.g. Ubuntu has had it enabled for more than a year now) than GCOV, so I'd prefer we maintain all*config coverage for the more commonly used config. > --- > lib/Kconfig.ubsan | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan > index f7cbbad2bb2f4..8f71ff8f27576 100644 > --- a/lib/Kconfig.ubsan > +++ b/lib/Kconfig.ubsan > @@ -29,6 +29,8 @@ config UBSAN_TRAP > > config CC_HAS_UBSAN_BOUNDS_STRICT > def_bool $(cc-option,-fsanitize=bounds-strict) > + # work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110074 > + depends on GCC_VERSION > 140000 || !GCOV_PROFILE_ALL > help > The -fsanitize=bounds-strict option is only available on GCC, > but uses the more strict handling of arrays that includes knowledge Alternatively, how about falling back to -fsanitize=bounds instead, as that (which has less coverage) wasn't triggering the stack frame warnings? i.e. fall back through these: -fsanitize=array-bounds (Clang) -fsanitize=bounds-strict (!GCOV || bug fixed in GCC) -fsanitize=bounds -- Kees Cook
